Mobiltechnológia

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Importance of Soil Quality in Environment Protection

Soil quality can be characterised by the harmony between it’s physical and biological state and the fertility. From the practical crop production viewpoint, some important contrasting factors of soil quality are: (1) soil looseness – compaction; (2) aggregation – clod and dust formation; friable structure – smeared or cracked structure; (3) organic material: conservation – decrease; (4) soil moisture: conservation – loss; water transmission – water-logging; (5) at least soil condition as a result of the long term ef ect of land use moderates or strengthens climatic harm. In our long-term research project practical soil quality factors were examined in arable i eld and experimental conditions. We state that prevention of the soil quality deterioration can be done by the developing and maintaining harmony between land use and environment. Elements of the soil quality conditions such as looseness, aggregation, workability, organic matter, water transport are examined and the improving methods are suggested. Tillage and production factors which can be adopted to alleviate the harmful climatic impacts are also summarised

Experimental and Numerical Failure Analysis of Adhesive Joint of Glass Fiber Reinforced Polymer Composite

The adhesive joint is the most widely used joining technique of thermoset composite structures. Analysis of the failure of adhesive joints of composite structures has a high importance due to its significance in industrial applications such as automobile or autobus bodies. In this paper we performed experimental and numerical analysis of a glass fiber reinforced, vinyl-ester matrix composite bonded with a methacrylate adhesive. The critical energy release rate in normal loading direction obtained from standard double cantilever beam test is used as input data in finite element simulations, in which the failure process is modeled by using cohesive zone material. Results of interface elements with exponential and standard contact elements with bilinear cohesive behavior are compared. The use of interface elements is numerically robust, convergence is reached faster, but identical mesh between the parts is needed. It can be a good alternative when simulating sub-models. When using standard contact elements, the robustness needs contact stabilization, however this method does not need identical mesh and it also allows the use of shell elements, therefore it can be used on a full-structure scale with high efficiency